Dooley Wilson got it wrong when he sang that a kiss is just a kiss. In fact, there’s nothing simple about the seemingly simple act of pressing one set of lips against another.

A kiss can be a formal peck on the cheek or a knee-weakening mash; a frightening first trip to first base, a healing touch on a skinned knee or an air smack that doesn’t come within an inch of a perfectly made-up face.

And around this time of year, a truly great kiss might be the easiest, cheapest and most heartfelt way of saying “I love you” to your valentine. That and a dozen roses.

Lynn Conger is looking forward to her Valentine’s Day kiss.

“My husband is the best kisser in the whole world,” says Conger, a Salt Lake City mother. “He has these sumptuous, soft lips.” Her husband, Russ Askren, will bring home one flower each for Lynn and the couple’s son, Simon, that day, and they will let the boy pick the restaurant they visit for dinner that night.

But the kiss will be for Lynn and Russ alone.

No one is sure how the tradition began, but some have theorized that kissing started when prehistoric mothers slipped chewed food from their lips into their babies’ mouths. Another theory says it was a way for our ancestors to better smell a potential mate and discover if he or she was healthy.

“The true origin of kissing remains a mystery,” said Vaughn Bryant, an anthropologist at Texas A&M University who has studied smooching for nearly 30 years.

But he says the first written records come from India, including the original bedside bible, the Kama Sutra, which features more than 200 passages devoted to kissing and offers suggestions for sensuous places to be kissed: the forehead, the eyes, the “tender part of the inside of the mouth,” the throat, the navel and other places.

While India may have perfected the erotic art, the Romans became “devoted missionaries” to it, helping spread kissing throughout Europe and ultimately the New World and Asia, according to Bryant.

Sometimes it was a hard sell, with many cultures seeing kissing as a filthy habit or a precursor to being eaten.

The Romans were the first to seal marital vows with a kiss, and they started the custom of a man kissing his wife upon his return home, perhaps as a way to ensure the missus hadn’t been hitting the vino, according to the book “Kissing,” by Andrea Demirjian.

Today, kissing is practiced by most cultures, and with good reason. It’s not only fun, it’s good for you. According to Demirjian, kissing can reduce stress and lower blood pressure. It prevents cavities and tooth decay by creating more saliva, which washes away plaque. It also plumps lips naturally, tones facial muscles and burns calories – 2 to 6 per minute, compared with 11 calories on the treadmill. It can even boost our immune systems, she writes.

“Kissing is every bit as good as chicken soup as a cure-all for most of your troubles,” Bryant says.

But the best part is the grand chemistry experiment that happens inside our brains when we smooch. Nerves in the lips, tongue and mouth – the highest concentration of nerves in the entire body – fire signals to the brain’s sensory cortex, says Helen Fisher, an anthropologist at Rutgers University and author of several books on the science of love.

The message gets relayed through the rest of the body, making the blood race, arteries swell and lungs pump.

“It’s an extremely powerful sensation that affects a huge section of the brain,” she says. “Not only do you get a lot of information about someone through touch (while kissing), but you also smell them, hear them, you can see them. You really feel them,” she said. “All of the senses are dramatically triggered.” The best kisses stir up an intoxicating cocktail of norepinephrine, dopamine and phenylethylamine, some of the same chemicals released when someone fires a gun, eats chocolate or parachutes from a plane, according to Demirjian.

To get the most out of it, though, you’ve got to be good. Cherie Byrd, a holistic psychologist and founder of the Kissing School in Seattle, says most of us could use a little work.

“People are missing out all over the place,” she says. Her No.

1 rule is to be completely attuned to the other person and what you’re offering him or her.

“Most people are kissing on the fly and really not allowing themselves the depths of connection in their own heart. They think, ‘I’ll kiss this person and then they’ll turn me on.’ It doesn’t work that way at all,” she says.

“We need to remember that it’s a communication. It’s a dialogue of tongues, a conversation of lips and nibbles and sounds and moans.” She has a few suggestions: “Keep your hands alive while kissing,” she says. Run them through you partner’s hair and along his or her lips. “That’s huge.” She’s also an advocate of open eyes.

“People need to look at each other, to really allow themselves to see one another,” she says.

Mark Owens, a Salt Lake psychologist who does marriage counseling, says kissing – good kissing – can be vital to a healthy marriage, especially one that’s floundering.

“That’s so important to build that kind of sweetness and intimacy. People are so busy. They really have to take time together, make it absolutely a priority,” he said.

One way to keep it exciting is to try new things.

“Take the kiss out of one context and put it in another,” says Fisher. “Say you’re walking down the street and he leans you up against the wall of a Greek temple. It’s a different feeling.” Vaughn Bryant advocates a little role playing, too.

He and his wife of 45 years, Carol, have re-enacted the “From Here to Eternity” kiss on the same beach where Burt Lancaster made out with Deborah Kerr. They’ve also replayed Rocky and Adrian at the steps of the Philadelphia Museum of Art.

“I would recommend everyone do that. Maybe if you do, you’ll be married for 45 years, too,” he says.

(The Salt Lake Tribune is a member of the MediaNews Group News Service.) NYT-02-11-07 1941EST